Bolt Technology Corporation

The Long-Life™ Air Gun

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Bolt Technology Corporation Long-Life™ Technology Solution

High Acoustic Output

During the early 1990s, the marine seismic industry began to develop larger and substantially more complex multi-streamer vessels capable of efficiently acquiring vast amounts of 3D seismic data. Bolt Technology Corporation introduced the Long-Life™ Air Gun in 1991, in response to demands by seismic contractors for a stable high endurance energy source that would match the efficiency of these vessels. The Long-Life™ design has resulted in air guns that consistently produce 500,000 or more trouble-free shots before requiring significant maintenance.

A combination of increased throat area and improved shuttle speed has resulted in a significant improvement over conventional Bolt Air Guns in both peak output and peak-to-bubble ratio. The following graph illustrates peak output vs. chamber volume for Bolt Long-Life™ Air Guns, measured through an Out-128 Hz filter.

1500-LL

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4 Bar-m

Since March of 1993 Bolt Technology Corporation has sold in excess of 4,800 Long-Life™ Air Guns, which equates to more than three fourths of the Western World’s seismic fleet. The following diagram illustrates the principle features of the Long-Life™ Air Gun.

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3 1900-LLXT

2 2800-LLX

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200

400

600

800

1000

Volume (cubic inches)

▲ Peak Output vs. Volume (Out-128 Hz Filter)

The Long-Life™ Air Gun is available in three models spanning volumes from 5 in³ to 1,500 in³. 2800-LLX The 2800-LLX Air Gun is designed for volumes ranging from 5 in³ to 120 in³. The gun is very light-weight, and is ideally suited for shallow water source vessels with limited deck space. For maximum energy output, it can be easily configured in 2–gun and 3-gun cluster elements.

▲ 1500-LL Long-Life™ Air Gun

The Long-Life™ Air Gun is available both as a completely new gun or as an upgrade kit for conventional 1500CT and 1900CT Bolt Air Guns.

▲ 2800-LLX Air Gun

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Bolt Technology Corporation 1900-LLXT

1500-LL 2-Gun Cluster

The 1900-LLXT Air Gun is designed for volumes ranging from 10 in³ to 250 in³. The gun is extremely versatile, and is sufficiently lightweight for shallow draught vessels while powerful enough for blue-water seismic surveys.

The preceding graph illustrating Peak Output vs. Volume for Bolt Air Guns clearly shows the effect of throat limitation on output. For each model of Air Gun, there is a volume limit beyond which the normal increase in output with volume is diminished.

▲1900-LLXT Air Gun

1500-LL

A solution to this problem is found in Bolt’s heavy-duty cluster spreader bar assembly. The increase in peak output for the 2-gun cluster compared to a single 600 in³ is shown in the following far-field signatures. 5

Cluster —–

3

Bar-m

Due to its large throat area, the 1500-LL Air Gun is capable of generating very high peak output with the excellent low-frequency content associated with large chamber volumes. Using heavy-duty cluster spreader bars, it is possible to configure cluster elements in excess of 1,000 in³ without sacrificing peak output.

▲ 2-Gun Cluster Frame (2 x 300 in³)

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Single Gun -3

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-5 0

50

100

150

200

250

Time (ms)

▲ Single 600 in³ vs. 2 x 300 in³ cluster

▲ 1500-LL Air Gun

The 1500-LL Air Gun produces the highest peak output over the largest range of chamber volumes. The gun can be configured with chamber volumes ranging in size from 40 in³ to 1,500 in³. Large chamber sizes require heavy duty towing frames to withstand the shock generated by the gun.

The far-field signature clearly shows the 20% improvement in efficiency that results from a 2gun cluster compared with a single 600 in³ air gun. Carefully engineered and thoroughly tested, Bolt’s Long-Life™ Air Gun has proven to be the marine seismic industry’s most reliable source for a decade. ®

Bolt Technology Corporation Bolt’s worldwide leadership as a supplier of seismic energy sources has been maintained by an on-going commitment to research and development. Bolt Technology Corporation prides itself in a long tradition of service to our customers. The company’s commitment to service and excellence is demonstrated by extensive quality control procedures and tests. In addition to inplant inspection, Bolt maintains an extensive test facility where each marine, land and borehole air gun is rigorously tested under conditions which simulate actual applications.

▲ Aerial View of Bolt’s Test Facility

Bolt is committed to being the premiere supplier of seismic energy sources for geophysical exploration.

▲ Bubble Venting from a 9000 in³ Air Gun at 10 m. depth

Bolt Technology Corporation Four Duke Place Norwalk, CT 06854 Phone: (1) 203 853 0700 Fax: (1) 203 854 9601 Bolt Technology Corporation 3024 Rogerdale Road Houston, TX 77042 Phone: (1) 713 784 8200 Fax: (1) 713 784 7158 www.bolt-technology.com [email protected]

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